res.render() doesn't work with bundled Express

Hi folks,

I’d like to use a templating engine with a function deployed in functions-framework style:

exports.index = (_, res) => {
  res.render("index.ejs");
};

I have also imported ejs engine in my package.json:

  "dependencies": {
    "ejs": "^3.0.2"
  },

However, when I invoke the deployed function, it fails with

Error: Cannot find module 'ejs'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)
    at Function.Module._load (internal/modules/cjs/loader.js:562:25)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at new View (/layers/google.nodejs.functions-framework/functions-framework/node_modules/express/lib/view.js:81:14)
    at Function.render (/layers/google.nodejs.functions-framework/functions-framework/node_modules/express/lib/application.js:570:12)
    at ServerResponse.render (/layers/google.nodejs.functions-framework/functions-framework/node_modules/express/lib/response.js:1012:7)
    at exports.(anonymous function) (/workspace/index.js:2:7)
    at process.nextTick (/layers/google.nodejs.functions-framework/functions-framework/node_modules/@google-cloud/functions-framework/build/src/invoker.js:243:17)
    at process._tickCallback (internal/process/next_tick.js:61:11)

On the other hand, when I modify the code to construct express object explicitly:

const express = require("express");
const app = express();

app.get("/", (_, res) => {
  res.render("index.ejs");
});

exports.index = app;

with

  "dependencies": {
    "ejs": "^3.0.2",
    "express": "^4.17.1"
  }

then it works.

Since the difference in these 2 cases seems to be that the 1st approach uses Express “bundled” with the Node.js 10 runtime, it seems like functions-framework is unable to resolve modules imported “implicitly” by the “bundled” Express.

That being said, when I run the function created with the 1st approach locally, using functions-framework --target=index, it works as expected. This seems to suggest that this is more of a problem with the runtime. Could you confirm if this issue belongs here or should I possibly open a ticket with Google support/tracker?

Thanks

[hdp617]

I think this is because of an optimization in production. The directory in the production environment is different from the local directory.

• Does it work if "express" is in package.json without constructing express object?
• Does it work if "@google-cloud/functions-framework" is in package.json?

[grant]

Thanks - could you share a link to the public tracker appropriate for this?

https://issuetracker.google.com/issues?q=status:open componentid:187195